The growth in the number of businesses using an internal network for geographically remote locations has been phenomenal in the past few years. An office in Dallas can have its own internal communications network separate and distinct from the networks of its sister offices in Los Angeles and Seattle. However, given the need to share data and resources between such distinct locations, high speed and high performance backbone links between such offices are usually leased by the parent company to connect the different networks. Clearly, such backbone links are expensive to lease from their providers. However, the businesses that lease these lines are looking for, among others, good application performance across the transport network or the network that transports the data between the two end networks.
Most, if not all, transport networks are packet based networks that break up larger pieces of data into smaller packets of data which are then transmitted from a first source network to a third destination network via a second transport network. However, due to congestion and other network limitations, not all packets successfully arrive at the destination network. It is this packet loss that the end networks seek to minimize and, consequently, the expensive high performance transport networks or links are leased.
What matters to the source and end destination networks is the performance of the transport network. The transport network must, from the point of view of the applications at the end networks, ideally be perfect with no lost packets. However, it would be preferred if such performance can be had for a price lower than the usual costs of leasing high performance transport networks.
Accordingly, there is a need for systems and methods which can be used with low cost communications transport networks to provide end network applications with a high performance view of the transport network.
Currently, two approaches have been tried to address the above situation. In one approach, the end networks employ custom protocols that are not greatly affected by data loss and latency. However, this approach requires extensive retooling as most systems use well accepted protocols such as TCP/IP. Such an approach may also result in chaos as there is no guarantee that such custom protocols will be interoperable with established end and transport networks.
Another approach involves using a custom protocol stack to transfer data across the transport network and initiating new TCP/IP sessions at the destination network. However, this approach is only useful for systems which use the TCP/IP protocol and other protocols, such as UDP/IP, may be affected by the latency and/or loss across the transport network.
It should be noted that the term data transmission unit (DTU) will be used in a generic sense throughout this document to mean units wich include transmitted data. Thus, such units may take the form of packets, cells, frames, or any other such units as long as data is encapsulated within the unit. Thus, the term DTU is applicable to any and all packets and frames that implement specific protocols, standards, or transmission schemes.